Debrazza’s monkeys are Old World monkeys from the family Cercopithecidae. The fossil record suggests that this family emerged and became abundant between 7-5 million years ago (Ma) in southern and western Africa. The greatest number of Cercopithecidae fossils found date from about 4-1.5 Ma. The first successful species were Parapapio and Theropithecus, which were much larger and slower than present species.

The Cercopithecidae family diverged from the hominoid lineage of Old World primates about 25 Ma, then split into two groups, Cercopithecine and Colobine, about 15 Ma. Within the Cercopithecine subfamily, the guenon lineage (which contains Debrazza’s monkeys) diverged from macaques, baboons, and mangabeys about 10 Ma.

Shared Derived Traits

Debrazza’s monkeys fall into a subgroup of the subfamily Cercopithecinaeknown as guenons. The 20 guenon species share many characteristics: bright coloration and markings, quadrupeds with longer arms than legs, short faces and short snouts, nonprehensile tails, relatively small size (up to 20 pounds), and cheek pouches for storing food. With regard to social behavior, guenons form uni-male groups and often forage and travel with other species.

Compared to other guenons, Debrazza’s monkeys tend to be bigger (around 15 pounds) and slower, and have distinct facial hair and coloration. They are also more polygynous than other guenons.

Shared Ancestral Traits

Monkeys are one group within the order of primates, consisting of about 200 different species across many different genera. Monkeys are generally distinguished from apes by the presence of a tail and a narrow chest, a short and flat face, and almost exclusively quadrapedal movement. They also tend to arboreal rather than ground-dwellers.

In contrast to New World monkeys, Old World monkeys (belonging to family Cercopithecidae) generally have narrow noses, ‘sitting pads’ (ischial callosities) on the buttocks, nonprehensile tails, and some have opposable thumbs.